A cooling apparatus of a false texturing machine

Abstract: A cooling apparatus of a high speed false texturing machine is provided by which so-called surging phenomenon is prevented, yarn breakages are not increased, unevenness in dyeing is not occurred, and deterioration of crimp characteristics in a obtained textures yarn does not occur. A false texturing machine comprises a false twisting device (5) for imparting twists to a yarn (2), a heating apparatus (3), disposed upstream the false twisting device (5), for heat setting twists run back along the yarn (2), and a cooling apparatus (4, 5), disposed between the heating apparatus (3) and the false twisting device (5), for cooling the yarn. The cooling apparatus (4) comprises a plurality of partial cooling plates (8). A yarn pressing member (9) serves to insert the yarn (2) into a space between the adjacent partial cooling plates (8) beyond a common contacting line of the adjacent partial cooling plates (8).

Description: BACKGROUND OF THE INVENTION Technical Field of the Invention The present invention relates to an improvement of a cooling apparatus of a false texturing machine, such as a draw texturing machine or a false twist texturing machine. More specifically, the present invention relates to a cooling apparatus of a false texturing machine, by which so called surging phenomenon can be prevented from occurring during high speed false twisting operation. The so called surging phenomenon means a phenomenon wherein a yarn generates a ballooning, i.e., a kind of rolling, of a yarn in a twisting zone when the false twist texturing speed is excessively increased, and abnormal variation in tension of the twisted yarn is resulted in. Prior Art A false texturing machine comprises a false twisting device for imparting twists to a yarn, and a heating apparatus, disposed upstream the false twisting device, for heat setting twists run back along the yarn. Further, a draw texturing machine is provided with a drawing device for drawing the yarn at a predetermined draw ratio prior to or simultaneously with the twist setting by the above-described heating apparatus and the false twisting device. Texturing machines of this type are known from US-A-3 368 335, CH-A-583 793 and FR-A-2 451 415. In a conventional operation, wherein false twist texturing speed is up to 100 m/min, it is sufficient for a yarn to be cooled by natural seasoning just after it is heat set by the heating apparatus. In other words, no specifically designed cooling apparatus is required. However, as the false twist texturing speed increases, the yarn cannot be fully cooled only by a conventional natural seasoning. In addition, when the twisted yarn runs at a high speed, ballooning at the cooling region increases. Thus, recently, a yarn is forced to run in contact with a cooling apparatus so as to restrict occurrence of the ballooning. When the false twist texturing speed is further increased and reaches a super high speed, i.e., a speed equal to or higher than 1,000 m/min, a surging phenomenon, i.e., a large waved vibration, occurs in a yarn running through the cooling apparatus. More specifically, the yarn is subjected to a ballooning, i.e., rolling, in the twisting zone, and abnormal variation in tension of the twisted yarn occurs. Especially when a high temperature heating apparatus, wherein a yarn is heated to a temperature higher than 300°C, is used, unevenness in dyeing or yarn breakages may occur easily. It is possible to increase the tension in yarn at the false twisting region in order to obviate the surging phenomenon. However, if this measure is adapted, crimp characteristic in the obtained textured yarn may be lowered and yarn breakages may be increased. consequently, the above-described measure, wherein tension in yarn at the false twisting zone is enhanced, has a limit for preventing the surging phenomenon. As another measure for preventing the surging phenomenon, it is possible to shorten the length of a cooling apparatus and to cool the cooling apparatus by means of water or another cooling medium. More specifically, the length of the cooling apparatus is shortened to about 500 mm, and two short cooling apparatus are prepared, and the yarn contacting surfaces of such cooling apparatus are forcedly cooled by means of cooling medium such as water. However, the construction of the cooling apparatus may be complicated if this measure is applied, and accordingly, the equipment cost and correspondingly the cost for manufacturing false textured yarns are increased. SUMMARY OF THE INVENTION Object of the Invention It is an object of the present invention to provide a cooling apparatus for a super high speed false texturing machine by which the above-described surging phenomenon can be prevented from occurring. The present inventors have examined thoroughly in order to achieve the above-described object, and noticed that the object can be achieved by improving construction of the cooling apparatus. Thus, the present inventors have achieved the present invention. Brief Description of the Invention According to the present invention, the above-described object is achieved by in a false texturing machine comprising a false twisting device for imparting twists to a yarn, a heating apparatus, disposed upstream the false twisting device, for heat setting twists run back along the yarn, and a cooling apparatus, disposed between the heating apparatus and the false twisting device, for cooling the yarn, wherein the cooling apparatus comprises a yarn contacting and cooling surface, at least one non-contacting portions are partially disposed in the yarn contacting and cooling surface of the cooling apparatus, and pressing members, for pressing the yarn at the non-contacting portions, are disposed correspondingly to the non-contacting portions. The characteristic feature of the present invention resides in that non-contacting portions are partially formed in a yarn contacting and cooling surface of the cooling apparatus, and that the yarn is pressed at the non-contacting portions by means of pressing members. Since the yarn is in contact with the pressing members, which are disposed corresponding to the non-contacting portions, as described above, the pressing members serve as nodes of the vibration, i.e., the ballooning. Accordingly, the resonance frequency of the yarn at the yarn cooling zone is enhanced. As a result, the surging phenomenon does not occur easily. In addition, since the yarn is pressed at the non-contacting portions by means of the pressing members, the tension in yarn is enhanced. As a result, the resonance frequency of the yarn at the yarn cooling zone is also enhanced, and accordingly, the surging phenomenon does not occur easily. According to the present invention, due to the prevention of occurrence of the surging phenomenon, the number of yarn breakages decreases as it will be confirmed by the example, and the crimp characteristic is increased. Thus, yarn having good quality and being free from unevenness in dyeing can be false textured at a super high speed higher than 1,000 m/min. Further, according to the present invention, it is preferred that the number of the non-contacting portions is set at least two as illustrated in the embodiment, and thus, the effect for preventing the surging phenomenon can be further enhanced. In this case, it is preferred that the respective yarn contacting and cooling surfaces divided by the non-contacting portions, the number of which is at least two, are formed in a convex shape, since the yarn runs in contact with the respective convex shaped yarn contacting and cooling surfaces divided by the non-contacting portions, and the effect for cooling the yarn is fully enhanced, and the tension in yarn can be maintained at a desired level. Similarly, it is preferred that the yarn contacting and cooling surfaces are as a whole formed in a convex shape, since the yarn runs in contact with the convex shaped yarn contacting and cooling surfaces, and the effect for cooling the yarn is fully enhanced, and the tension in yarn can be maintained at a desired level. It is especially preferred that a length of a yarn contacting and cooling surface is between 100 and 500 mm, and a total length of a plurality of yarn contacting and cooling surfaces is between 1,000 and 3,000mm, and at least one of angles formed between a common imaginary contacting line for adjacent two yarn contacting and cooling surfaces divided by the non-contacting portion and a yarn pressed by the pressing member exceed 0 o and less than 30° as shown in the embodiment. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will now be explained in detail with reference to the accompanying drawings, wherein: Fig. 1 is a side view schematically illustrating a high speed false texturing machine; Fig. 2 is a side view of a cooling apparatus of the present invention illustrated in Fig. 1; Fig. 3 is a partially enlarged view of Fig. 2; and Fig. 4 is a side view of another embodiment of a cooling apparatus of the present invention. PREFERRED EMBODIMENTS The present invention will now be explained in detail with reference to the accompanying drawings illustrating embodiments of the present invention. Referring to Fig. 1, which is a side view schematically illustrating a high speed false texturing machine, a yarn 2 withdrawn from a supply package 1 is wound into a package by means of a take-up 7 after it passes a heating apparatus 3, cooling apparatus 4 and 5, and a false twisting device 6. Twists imparted by the false twisting device 6 run back along the yarn 2 towards the heating apparatus 3, and the twists are heat set by means of the heating apparatus 3 and the cooling apparatus 4 and 5. More specifically, heat setting is done by cooling the yarn 2, which has been heated by the heating apparatus 3, by means of the cooling apparatus 4 and 5. Fig. 2 is a side view of the cooling apparatus 4 illustrated in Fig. 1, and Fig. 3 is a partially enlarged view of Fig. 2. Referring to Fig. 2, a plurality of partial cooling plates 8 and 8, which have a convex surface, respectively, are disposed in such a manner that they form a small distance therebetween, which distance forms a non-contacting portion, and that they as a whole form a convex shape. Thus, the cooling apparatus 4 is formed. The reason why a plurality of partial cooling plates 8 and 8 have a convex surface, respectively, and why the cooling apparatus formed by a plurality of partial cooling plates 8 and 8 as a whole form a convex shape is to enhance contacting efficiency of the yarn 2 to the partial cooling plates 8 and 8 and the cooling apparatus 4, and thus, to increase cooling efficiency and at the same time to maintain a desired tension in yarn. The required characteristics of the material suitable for the partial cooling plates 8 are that it can cool a yarn 2 quickly, that it is resistant to friction, that it has a low coefficient of friction against fibers and that its cost is inexpensive. For example, steel plate may be used for such a cooling plate 8. In the small distance between the partial cooling plates 8 and 8, i.e., at the non-contacting portion, yarn pressing members 9 are located beyond imaginary lines connecting the surfaces of the adjacent partial cooling plates 8 to positions under the surfaces of the partial cooling plates 8. The yarn pressing members 9 may be movable perpendicular to the yarn passage, and the yarn pressing member 9 may be moved from a operational position illustrated in Figs. 2 and 3 to a stand-by position, which is away from the operational position, upon threading so as to facilitate easy threading up to the cooling apparatus 4. Alternatively, the yarn pressing members 9 may be disposed at stationary positions at the small distance between the partial cooling plates 8 and 8, i.e., non-contacting portions, inserted beyond the yarn passage. Fig. 3 is an enlarged view illustrating the locational relationship between the partial cooling plate 8 and the yarn pressing member 9. The angle "a" and "b" denote the following amounts. More specifically, the angle "a" denotes an angle formed between a common imaginary contacting line 2' for the yarn contacting surfaces of adjacent two partial cooling plates 8 and a yarn leaving from one of the partial cooling plates to the pressing member 9, while the angle "b" denotes an angle formed between the common imaginary contacting line 2' for the yarn contacting surfaces of adjacent two partial cooling plates 8 and a yarn leaving from the pressing member 9 to the other partial cooling plates 8. The yarn pressing member 9 may be a stationary pin, and alternatively, it may be a turnable member, such as a roller, in some cases. The above-described cooling apparatus 4, i.e., the partial cooling plates 8, may be cooled by natural seasoning by means of radiation or convection, however, in some cases, it may be cooled by means of cooling medium, such as water or the like, if desired. In the above-described embodiment, the partial cooling plates 8 and 8 were separated and independent from each other. However, the partial cooling plates 8 may be formed integrally as illustrated in Fig. 4. Although the above-described explanation was done with reference to the cooling apparatus 4, the cooling apparatus 5 may be constructed in a manner similar to that of the cooling apparatus 4. In some cases, the cooling apparatus 5 may have a construction similar to a conventional one. Generally speaking, as the false twist texturing speed increases, the length of the cooling apparatus increases in order to surely cool a yarn. When the length of the cooling apparatus increases, a yarn tends to generate ballooning at the cooling apparatus as described above. In a conventional apparatus, when the texturing speed reaches 1,000 m/min, the surging phenomenon occurs as described above, and a stable texturing operation cannot be expected. In order to prevent such a surging phenomenon, according to the present invention, the cooling apparatus is constructed with a combination of short partial cooling plates 8, and yarn pressing members 9 are disposed at non-contacting portions formed between the partial cooling plates 8. As a result, according to the present invention, a yarn 2 is inserted by means of the yarn pressing members 9 to a position towards the inside of the partial cooling plates 8, i.e., lower position under the yarn contacting surfaces of the partial cooling plates 8, beyond the imaginary contacting line 2' connecting the yarn contacting surfaces of the partial cooling plate 8. Especially when the partial cooling plates 8 are formed in a convex shape, the yarn 2 is pressed by means of the yarn pressing members 9 to a position opposite to the top of the convex shape formed by the partial cooling plate 8 relative to an imaginary curve along the yarn contacting surface of the convex shaped cooling apparatus 4. The curvature of the cooling apparatus 4 may be appropriately selected. As the length of the partial cooling plates 8 decreases, the surging phenomenon can be prevented from occurring. However, when the total length of the cooling apparatus 4 is constant, the number of the yarn pressing members 9 increases if the length of the respective partial cooling plates 8 is shortened. If the number of the yarn pressing members 9 is excessively increased, run back of twists may be deteriorated or yarn breakages may occur easily. When the inserting depth of the yarn pressing member 9 beyond the imaginary curves 2-2'-2 on the cooling apparatus 4 increases, in other words, when the angles "a" and "b" increase, the surging phenomenon can be prevented from occurring. However, if the angles "a" and "b" are excessively large, run back of twists may be deteriorated or yarn breakages may occur easily. According to the technical investigation performed by the present inventors, it is ideal that the length of the partial cooling plates 8 is shortened to an amount between 30 and 50 mm, that the number of the yarn pressing members 9 is increased, and that both the angles "a" and "b" are selected to a small amount, for example about 3°. However, when such requirements are fully met, the manufacturing cost of the cooling apparatus will be expensive. In addition, knotted portions in a yarn may not smoothly pass through the yarn pressing members, the number of which is excessively large. Thus, difficulty in operational management was often observed. Taking into consideration the background described above, it is most preferable to prevent the surging phenomenon that the length of the partial cooling plates 8 is at least about 100 mm, and the recommended maximum length is about 300 mm. When the length of the partial cooling plates exceeds the recommended maximum length, the angles "a" and "b" have to be increased to a sufficiently large amount in order to achieve the effect for preventing the surging phenomenon, and as a result, frequency of yarn breakage increases. Further, according to the investigation conducted by the present inventors, when the angles "a" and "b" are equal to 0°, any remarkable effect cannot be observed since the yarn is scarcely in contact with the yarn pressing members 9. When the angles "a" and "b" exceed 0°, effect can be observed, and it is confirmed that the preferred angles "a" and "b" are between 3° and 30° from good run back of twists and small yarn breakage. Especially, the most recommended angles "a" and "b" are between about 3 o and about 10 o . In this case, when the number of the yarn pressing members 9 increases, run back of twists is not disturbed, and a yarn is not damaged hardly, and therefore, occurrence of yarn breakages does not increase. Examples In a false texturing machine illustrated in Fig. 1, the total length of the cooling apparatus 4 was 1,400 mm, and the radius of carvature was 4m. The cooling apparatus 4 was equally divided into 3, 5 and 8 partial cooling plates 8, In all the cases, the distance between the adjacent partial cooling plates 8 was 15 mm. Ceramic bars, having a diameter of 5mm, were prepared as yarn pressing members. Four levels, 0°, 5°, 15°, 30°, were prepared for the angle "a" and "b". The cooling apparatus 5, which was disposed downstream the cooling apparatus 4, was 300 mm long. The heating apparatus 3 was a high temperature heater of a non-contacting type, having 1,200 mm length and comprising two stages. The upper stage of the heating apparatus 3 was 400 mm long, and was always set to a temperature of 500°C. The lower stage of the heating apparatus 3 was 800 mm long, and was set to a temperature of 300°C at a texturing speed of 1,000 m/min, 360°C at a texturing speed of 1,300 m/min, and 420°C at a texturing speed of 1,600 m/min. The false twisting device was a false twisting device of a friction type. The supply yarn 1 was polyester POY, i.e., partially oriented yarn, of 115 de/36 fil, and was subjected to a simultaneous draw and texturing operation at draw ratio of 1.53. The results are shown in Table 1. In Table 1, O denotes good, X denotes bad, and - shows that measurement of physical properties of the obtained textured yarn was impossible since the conditions created a number of yarn breakages. Since good effects were observed at angle "a" of 5° at a texturing speed of 1,000 m/min, experiences at angle "a" of 15° or 30°, wherein a yarn will be subjected to a large load, were omitted. According to the present invention, non-contacting portions are partially formed in a yarn contacting and cooling surface, and the yarn is pressed at the non-contacting portions by means of pressing members. Since the yarn is in contact with the pressing members, which are disposed corresponding with the non-contacting portions, as described above, the pressing members serve as nodes of the vibration, i.e., the ballooning, and accordingly, the resonance frequency of the yarn at the yarn cooling zone is enhanced. As a result, the surging phenomenon does not occur easily. In addition, since the yarn is pressed at the non-contacting portions by means of the pressing members, the tension in yarn is enhanced. As a result, the resonance frequency of the yarn at the yarn cooling zone is also enhanced, and accordingly, the surging phenomenon does not occur easily. According to the present invention, due to the prevention of occurrence of the surging phenomenon, the number of yarn breakages decreases, and the crimp characteristic is increased. Thus, yarn having good quality and being free from unevenness in dyeing can be false textured at a super high speed higher than 1,000 m/min.

Claims: A false texturing machine comprising a false twisting device (6) for imparting twists to a yarn (2), a heating apparatus (3), disposed upstream said false twisting device, for heat setting twists run back along said yarn, and a cooling apparatus (4, 5), disposed between said heating apparatus (3) and said false twisting device (6), for cooling said yarn, characterized in that said cooling apparatus (4) comprises a yarn contacting and cooling surface (8), at least one non-contacting portion being partially disposed in said yarn contacting and cooling surface of said cooling apparatus, and that pressing members (9), for pressing at said yarn into said non-contacting portions, are disposed correspondingly to said non-contacting portions. A false texturing machine according to claim 1, wherein the number of said non-contacting portions is at least two. A false texturing machine according to claim 1 or 2, wherein said respective yarn contacting and cooling surfaces (8) of said cooling apparatus divided by said non-contacting portions are formed in a convex shape. A false texturing machine according to one of the claims 1 to 3, wherein yarn contacting and cooling surfaces (8) of said cooling apparatus are as a whole formed in a convex shape. A false texturing machine according to claim 1, wherein a length of a yarn contacting and cooling surface (8) of said cooling apparatus is between 100 and 500 mm, and a total length of a plurality of yarn contacting and cooling surfaces of said cooling apparatus is between 1,000 and 3,000 mm, and at least one of angles (a, b) formed between a common imaginary contacting line for adjacent two yarn contacting and cooling surfaces divided by said non-contacting portion and a yarn pressed by said pressing member exceeds 0° and less than 30°.

Inventors: HINO HAJIME, IKEUCHI TAKASHI, NAKAHARA TEKEICHI, OGISO TSUTOMU, HINO, HAJIME, IKEUCHI, TAKASHI, NAKAHARA, TAKEICHI, OGISO, TSUTOMU, HINO, HAJIME, C/O TEIJIN SEIKO CO., LTD., IKEUCHI, TAKASHI, C/O TEIJIN SEIKO CO., LTD., NAKAHARA, TEKEICHI, C/O TEIJIN SEIKO CO., LTD., OGISO, TSUTOMU, C/O TEIJIN SEIKO CO., LTD.
Applicants: TEIJIN SEIKI CO LTD, TEIJIN SEIKI CO. LTD.
Application year: 1994
Main classification: D02J13
IPC codes: D02G1, D02J13